A typical reciprocating saw blade comprises a blade portion having a cutting edge defined by a plurality of teeth axially spaced relative to each other along one side of the blade, and a non-working edge formed on an opposite side of blade relative to the cutting edge. A tang for releasably connecting the blade to the chuck of a reciprocating saw has a tang body formed on the inner end of the blade and a tang stem formed on the inner end of the tang body. Typically, the tang defines an aperture therein for receiving a drive pin of a chuck. In order to fit properly within a chuck, the tang defines a more narrow width than the blade portion, and the tang stem defines a more narrow width than the tang.
Keyed chucks on reciprocating saws typically define a relatively narrow space for receiving the tang. In these types of chucks, the tang is fixedly engaged by the chuck throughout a relatively large surface area of the tang to fixedly secure the tang and tang stem of the blade within the chuck. In keyless chucks, on the other hand, a drive pin is received within the hole formed in the tang, and the chuck typically engages the tang stem so that its base, i.e., at the juncture of the tang and its stem, is subjected to relatively high stress loads. The forces created upon engaging a work piece with the reciprocating cutting edge of the blade create a moment about the drive pin engaging the hole in the tang. The torque at the drive pin creates relatively high stresses at the juncture of the tang and stem, and at the area extending between the points of tangency of the curvilinear portions of the tang formed at the juncture of the tang and blade portion. For example, tensile stresses are created at the inner areas of these blade portions (i.e., at the areas located on the cutting side of the blade), and compressive stresses are created at the outer areas of these blade portions (i.e., at the areas located on the non-working side of the blade). As a result, reciprocating saw blades typically fail at the juncture of the tang and stem, and/or at a line extending approximately between the points of tangency of the curvilinear portions of the tang formed at the juncture of the tang and blade portion.
Certain chucks have internal obstructions that require a relatively narrow tang stem to properly fit a reciprocating saw blade within the chuck. Other chucks do not have such obstructions. However, as described above, chucks typically engage the tang with a drive pin, and along the front edge of both the tang body and tang stem such that the juncture of the tang body and tang stem can be subjected to relatively high stresses. Thus, although it would be desirable to increase the width of the tang stem, particularly for use in chucks free of internal obstructions, in order to better withstand the tensile and compressive stresses created at the juncture of the tang body and tang stem, the overall width of the tang stem cannot be significantly increased without interfering with internal components associated with certain chucks. In addition, it would be desirable to increase the width of the tang at the juncture of the tang body and the cutting portion of the blade to better withstand the tensile and compressive forces created in this area during cutting. However, the width of the tang in this area cannot be significantly increased without preventing the tang from properly fitting within certain conventional reciprocating saw chucks.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantage of prior art reciprocating saw blades, and to provide a reciprocating saw blade that better withstands the forces which are created between the tang stem and the chuck, which typically result in stress and fatigue at the juncture of the tang body and the tang stem.